Oil well cementing process

ABSTRACT

Oil well cementing compositions and processes are produced using a high efficiency sulfoalkylated lignin retarder composition and modifications thereof to produce cement compositions without gelation problems, having high early strength and with precisely controllable setting time.

This invention relates to cement compositions and more particularly tothe use of hydraulic cement compositions for sealing or cementingsubterranean zones or subterranean zones penetrated by a well such ascementing the annular space in an oil well between the surroundingformation and casing. In particular the invention relates to an improvedhydraulic cement composition for cementing zones at elevatedtemperatures in which the setting time of the cement composition iscontrolled or extended by the addition of a highly efficient non-gellingretarding agent which produces a hydraulic cement composition having adegree of predictability for the setting time.

Typically, the subterranean zones are cemented or sealed by pumping anaqueous hydraulic cement slurry into the zone. In cementing the annularspace of an oil well, the cement slurry is pumped down the inside of thecasing and back up the outside of the casing through the annular space.Any cement slurry remaining in the casing is displaced and segregatedusing plugs and an aqueous displacement fluid. Frequently the hightemperatures encountered in subterranean zones will cause prematuresetting of the hydraulic cement. This requires additives which extend orretard the setting time of the cement slurry so that there is adequatepumping time in which to place and displace the aqueous cement slurry inthe desired zones. Previously known retarding agents are frequentlyunpredictable, typically produce erratic results with different brandsof cement and frequently cause premature gelation of the cement slurry.Gelation refers to an abnormal increase of viscosity of the aqueouscement slurry to a value without a significant increase in thecompressive strength of the cement composition. This increase in aqueouscement slurry viscosity makes the slurry difficult or impossible to pumpat a viscosity of 70 poise or above which is defined as the set pointherein. The cement composition has not attained an adequate compressivestrength.

Prior art cement compositions and additives are described in thefollowing list of 14 patents:

U.s. pat. No. 2,549,507 to Morgan et al

U.s. pat. No. 2,579,453 to Post et al

U.s. pat. No. 2,674,321 to Cutforth

U.s. pat. No. 2,676,170 to Patterson et al

U.s. pat. No. 2,680,113 to Adler et al

U.s. pat. No. 2,775,580 to Scarth

U.s. pat. No. 2,872,278 to Putnam et al

U.s. pat. No. 3,034,982 to Monroe

U.s. pat. No. 3,053,673 to Walker

U.s. pat. No. 3,135,727 to Monroe

U.s. pat. No. 3,344,063 to Stratton

U.s. pat. No. 3,748,159 to George

U.s. pat. No. 3,766,229 to Turner

U.s. pat. No. 3,821,985 to George.

Fundamentals of oil well cementing are described in the book PETROLEUMENGINEERING DRILLING AND WELL COMPLETIONS, by Carl Gatlin, PrenticeHall, 1960. Background of and information on hydraulic cementcompositions and additives can be found in the following books:

LIGNIN STRUCTURE AND REACTIONS, ADVANCES IN CHEMISTRY SERIES, 1959,American Chemical Society, 1966;

MECHANICAL BEHAVIOR OF HIGH POLYMERS, by Turner Alfrey, IntersciencePublishers, 1948; and

HACKH'S CHEMICAL DICTIONARY, 4th Ed., McGraw-Hill, 1969.

The above references and information cited therein are incorporatedherein by reference to the extent necessary.

The hydraulic cement compositions of this invention solve or eliminatemany of the problems pointed out above. The hydraulic cementcompositions of this invention do not have the gelation problem; theretarder composition is more efficient than prior art retardercompositions, the retarder has less variation with different brands ofcement; cement compositions have much better predictability orreproducibility of setting times with a given brand of cement; andhydraulic cement compositions have better rheology characteristics. Thusthe improved cement compositions of this invention have practicallyeliminated the problems of unpredictability and irreproducibility ofresults which are particularly severe in high pressure deep wells wherethe temperatures may exceed 300° F and 15,000 PSI.

The concentration of retarder composition of this invention required toproduce the desired pumping time for or delay in setting of a cementslurry at a given circulating temperature is not as critical as withconventional lignosulfonate retarders. The thickening time at a givenretarder concentration is less temperature dependent than withconventional retarders. This reduces the possibility of over retardedslurries at cooler temperatures encountered at the top of long liners ortie back strings. The retarder compositions of this invention providethe desired pumping times and allow earlier strength development. Whencementing long strings this can reduce the WOC (waiting on cement toset) time by 8-12 hours. Thus, the retarder compositions of thisinvention are more predictable in performance than conventionallignosulfonate retarders especially with various brands of cement. Thecompositions of this invention act not only as retarders but also as adispersing agent which can reduce fluid loss from gel type or high claycement slurries. When the retarder composition of this invention isblended in a cement slurry, viscosity of the slurry decreases slightlyand remains constant or does not increase significantly until the cementbegins to set. This improvement in rheology or viscosity characteristicswith improved predictability makes use of the compositions much easierthan with conventional retarders. In addition, the retarder compositionsof this invention are generally non-toxic, non-flammable, non-hazardous;compatible with cements, other additives and with most other well fluidsand mix readily in aqueous systems with minimum agitation.

The high efficiency, non-gelling cement retarder composition of thisinvention has a high degree of predictability for controlling rheologyand setting time of hydraulic cement comprising a low molecular weightsulfoalkylated lignin which is substantially sulfoalkylated in thelignin molecule at positions on the benzene ring which are ortho to thephenolic hydroxyl group. In the sulfoalkyl group the sulfonic acid group(--SO₃ H) is connected to the ortho position on the benzene ring by amethylene or substituted methylene groups. This methylene or substitutedmethylene group is referred to herein as an alkylidene radical havingone to five carbon atoms. This alkylidene radical with sulfonic acidradical can be represented by the formula (--R--SO₃ H) wherein R is themethylene group or alkyl portion having one to five carbon atoms andpreferably one to three carbon atoms.

The unexpected properties of this retarder are thought to be due to thedifferences in average molecular weight or average molecular size andmolecular structure. The evidence showing these differences isillustrated in the examples which show the unexpected properties. Thesulfoalkylated lignin of this invention is a low molecular weightmaterial having an average molecular weight or molecular size in therange of about 2,000-10,000 and preferably about 3,000-5,000. It is alsothought to have a narrow molecular weight distribution. Prior artlignosulfonate compounds have a molecular weight or molecular size ofabout 10,000 and higher and the sulfonate substituent or radicalattached directly on the carbon atom of the lignin molecule which is inthe alpha position of the phenyl propyl side chain. This phenyl propylor aliphatic chain is attached at a position on the benzene ring whichis para to the phenolic hydroxyl group discussed herein. Forlignosulfonate the phenolic hydroxyl group can be replaced by an alkoxygroup as indicated by R₁ --Ph--OR₂ wherein R₁ is the phenyl propyl sidechain, Ph is phenyl or the benzene ring and R₂ is hydrogen or alkyl. Thesulfoalkylated retarder composition of this invention has substantiallyall of the sulfoalkyl group (i.e., --R--SO₃ H) in the position ortho tothe phenolic hydroxyl group of the benzene ring of the lignin molecule.

The sulfoalkylated lignin retarder of this invention does not have asignificant degree of sulfonation at the alpha carbon atom as do theprior art lignosulfonates. Thus, the sulfoalkylated lignin retarder ofthis invention is an entirely different chemical composition as shown bythe unexpected and significantly different properties shown herein. Thesulfoalkylated lignin retarder of this invention can be considered to bea sulfoalkylated lignin of high purity, low molecular weight with anarrow molecular weight distribution. This is thought to be due to thesignificantly different procedure used for its preparation.

The sulfoalkylated lignin retarder for compositions of this inventioncan be prepared by catalytic oxidation of the sulfite liquor from a woodpulping process. This oxidation removes polysaccharides and wood sugarsand substantially desulfonates the lignin molecule which is recovered asa residue. This purified lignin is separated from the liquor. The highpurity, low molecular weight lignin molecule is then substantiallysulfoalkylated by the addition of sulfonating agent such as sodiumsulfite in the presence of an aldehyde or ketone having one to fivecarbon atoms at about 150°-190° C and 180-220 atmospheres. In thisprocess, the aldehyde or ketone furnishes the alkylidene group whichattaches at a vacant ortho position on the benzene ring in the ligninmolecule and connects the sulfonate group through a methylene radical tothe benzene ring at a position ortho to the free phenolic hydroxylgroup. Some benzene rings may have more than one sulfoalkyl groupattached and some benzene rings may have no sulfoalkyl substituents. Thesulfur content of the sulfoalkylated lignin is between about 3-10% andpreferably 3-8%.

This sulfonate group can be in the form of the acid, a salt orcombinations thereof. The salt can be in the form of ammonium or metalsalt involving an alkali metal; an alkaline earth metal; or metals suchas iron, copper, zinc, vanadium, titanium, aluminum, manganese,chromium, cobalt or nickel; or combinations thereof. The salts which arereadily soluble in aqueous systems, such as those of the alkali metals,sodium and potassium, are preferred although the salts of alkaline earthmetals and other metals can be used under certain circumstances.

The alkyl portion of the sulfonate substituent is derived from thealdehyde or ketone used in the sulfoalkylation step. Formaldehyde is apreferred alkyl source because it simply connects the sulfonate group tothe ortho position by a one-carbon atom methylene group. Acetone wouldproduce an alkylidene group having a methyl group on each side of themethylene group; methyl ethyl ketone would result in a methyl and anethyl alkyl group attached to the methylene group; and propionaldehydewould result in an ethyl group attached to the methylene bridge.Theoretically, any aldehyde or ketone could be used for forming thealkylidene radical but the stereo chemistry and solubility must beconsidered in selecting the size and configuration of the aldehyde orketone use for this component. A preferred sulfoalkylated lignin of thisinvention has a molecular weight in the range of about 3,000-4,000, aone carbon atom alkylidene radical and a sulfur content of about 3-8% byweight.

Another preferred hydraulic cement composition of this invention can beconsidered to be a modified low molecular weight sulfoalkylated lignin.This modified retarder composition is a combination of the high puritysubstantially sulfoalkylated lignin described above and at least onewater soluble hydroxy carboxylic acid. These hydroxy carboxylic acidshave a synergistic effect of increasing the effectiveness and operabletemperature range of the basic retarder composition. The preferredcarboxylic acids are substantially alphatic carboxylic acids andpreferably polyhydroxy carboxylic acids having at least one terminalcarboxy group which can be in the form of the acid, a salt or mixturesthereof as described above for the sulfonate groups.

Particularly preferred polyhydroxy carboxylic acids have a molecularweight in the range of about 125-250 and have a hydroxyl group attachedto the carbon atom adjacent to the carboxy group as show by the formula##STR1## These carboxylic acids include gluconic acid, tartaric acid andequivalents thereof. These equivalents include the various stereoisomersof the above acids particularly the asymmetric or optically activeisomers. Thus, the preferred group of hydroxy carboxylic acids aresubstantially linear aliphatic acids having about 4-10 carbon atoms, andpreferably 4-8 carbon atoms. The molecular size and number of hydroxyand carboxylic groups will affect the water solubility. The hydroxycarboxylic acid is preferably present with the sulfoalkylated lignin ina weight ratio of acid to lignin preferably in the range of about1:0.1-5.0 and preferably in the range of about 1:0.2-3.0.

The hydraulic cement compositions of this invention are typically usedin the form of an aqueous slurry of hydraulic cement with aconcentration of retarder mixed in the aqueous slurry to control ordelay the cement setting time so that it exceeds the pumping time withan adequate safety margin. Sufficient water is added to the slurry tomake the composition pumpable. As used herein the hydraulic cement istypically a Portland cement which is set by the water of the slurry inthe absence of air which is excluded by placement of the cement in thezone to be sealed. The low molecular weight sulfoalkylated ligninretarder of this invention is preferably present in the aqueoushydraulic cement slurry in a concentration up to about 2%, andpreferably up to 1%, by weight based on the dry cement. Higher retarderconcentrations and other cement can be used when necessary in unusualcircumstances. A deforming agent is typically added as are fluid lossadditives, friction reducing additives, salts such as sodium chlorideand potassium chloride, weighting additives and other conventionaladditives as described in the references cited above. Pozzolana cement,high alumina cement or high gel (high clay content) cement can be usedfor special applications. The low molecular weight sulfoalkylatedretarder composition of this invention has high reproducibility andpredictability when used with most high quality cements which aretypically used in the petroleum industry. However, certain brands whichare not manufactured to standard specifications, such as those which arenot sufficiently calcined or having varying degrees of free limeremaining in the cement, will produce substantial variations from thestandard high quality brands. It is not clear whether the free limecauses the problems or is merely an indication when the problems exist.These variations can be readily determined by preliminary tests whichmake even these substandard cements readily predictable and may merelyrequire slightly higher retarder concentrations to offset the chemicalcomposition variations of the cement of excess lime content.

In a preferred process for using the non-gelling hydraulic cementcomposition of this invention having a degree of predictability ofsetting time and containing the high efficiency retarder, the retardercomposition is mixed with the hydraulic cement as an aqueous slurry withthe retarder concentration up to about 2% on a dry cement weight basis.The hydraulic cement mixture is pumped without gelation into the zone tobe sealed or cemented and the hydraulic cement mixture is maintained inthe zone until an adequate compressive strength is attained. In thisprocess the retarder concentration preferably up to about 2% on a drycement weight basis is calculated to control the setting time of thehydraulic cement slurry to exceed the pumping time within an adequatesafety margin. Due to the higher efficiency of the retarder and greaterpredictability of the hydraulic cementing compositions of thisinvention, the portion of the safety margin previously required forthese variations can be substantially reduced. The safety margin nowneed primarily allow time only for unexpected equipment difficulties.This reduction in the safety margin time or time which the typical oildrilling rig is waiting for the cement to set can result in asubstantial economic advantage due to the higher efficiency andpredictability of the hydraulic cement compositions of this invention.The modified low molcular weight sulfoalkylated lignin of this inventionor the combination of the sulfoalkylated lignin with the hydroxycarboxylic acids improve the efficiency and predictability of thecompositions of this invention even more and therefore are preferablyused. The basic sulfoalkylated lignin retarder composition of thisinvention can be used up to a temperature (i.e., BHCT) slightly inexcess of about 210° F and the modified retarder composition containingthe hydroxy carboxylic acids can be used up to a temperature of about400° F.

The molecular weight of the sulfoallkylated portion of the compositionof this invention is determined by diffusion techniques. Thesedifferences between the sulfoalkylated lignin compositions of thisinvention and the prior art lignosulfonates are shown by the examples.

The following examples serve to illustrate various embodiments of theinvention and enable one skilled in the art to practice the invention.Parts, percentages, proportions and concentrations are by weight unlessindicated otherwise.

Samples of calcium (CaLS) and sodium lignosulfonates (NaLS) and apreferred sulfomethylated lignin (SML) composition of this inventionwere analyzed chemically by spectroscopy using X-ray, infrared, andultraviolet radiation techniques. The samples were prepared and analyzedby standard procedures such as those described in ABSORPTIONSPECTROSCOPY, by Robert P. Bauman, John Wiley & Sons, Inc., 1962, whichis incorporated herein by reference to the extent necessary. X-raydiffraction merely showed that both the lignosulfonate andsulfoalkylated lignin were noncrystalline.

Chemical analysis indicated the following constituents by weight:

    ______________________________________                                               % C     % H.sub.2  % Ca       % S                                      ______________________________________                                        CaLS     39.1      4.3        7.6      3.9                                    NaLS     42.2      4.6        0.3      7.4                                    SML      45.0      3.8        0.2      6.2                                    ______________________________________                                    

The sulfur content of NaLS and SML was thought to include some inorganicsulfur (e.g. CaSO₄) entrained from cation exchange or sulfonationliquor.

For ultraviolet (UV) technique which scanned 190-360 millimicrons (mμ)for both NaLS and SML showed a major peak at about 202-205 millimicronswith shoulder or decreasing peaks at about 230 and 310-320 millimicrons.The samples were in water at a 0.02 gram per liter concentration andwere run in a one cm path length cell.

The infrared (IR) transmittance scan from 2.5-30 microns or 300-400 cm⁻¹showed peaks at the following wave lengths (λ) in cm⁻¹ :

NaLS*3440; 2940; 2840*; 1590; 1495; 1450; 1415; 1250*; 1200; 1140*;1035; 930*; 640 and 590.

Sml: 3440; 2940; 2840; 1675; 1590; 1495; 1450; 1415;

1355; 1250*; 1200; 1140*; 1070; 1035; 930*; 850; 775; 735; 590 and 525.

The starred values (*) are shoulder peaks or peaks which are not verydistinct. Samples for the IR scan were mulled in NUJOL mineral oil andrun between salt plates.

EXAMPLES

For the following examples each sample was prepared by measuring an800-gram portion of the designated dry cement into a cylindricalcontainer of approximately 800 milliliters volume. Dry or powderedadditives are designated as a percentage of the weight of the drypowdered cement unless indicated otherwise. Dry powdered additives aremeasured and blended with cement. A portion of tap water equal to theweight percentage of the dry cement is slurried with the dry cement andadditives with vigorous mixing. The slurry is stirred for an additional30 seconds at a high rate. Liquid additives are blended into the water.Samples were tested according to standard procedures as set forth in APIMethod RP-10B which is incorporated herein by reference.

For thickening time tests a sample portion is stirred in a container ofabout 500 milliliters at a temperature and pressure schedule determinedby API method RP 10B. The container is heated from ambient temperatureunder pressure. It contains a direct reading consistometer which iscalibrated with a potentiometer calibrating device to read directly inunits of consistency (API-RP-10B). The set time or setting point is thetime or point at 70 units of consistency or viscosity.

API Method RP-10B provides the following casing schedule for bottom holecirculating temperature (BHCT) and bottom hole static temperature (BHST)at the indicated depths:

    ______________________________________                                        Depth (ft.) BHCT (° F)                                                                           BHST (° F)                                   ______________________________________                                         8,000 (2440 m)*                                                                          125 (51.67° C)*                                                                      200 (93.33° C)*                              10,000 (3050 m)                                                                           144 (62.22° C)                                                                       230 (110.00° C)                              12,000 (3660 m)                                                                           172 (77.78° C)                                                                       260 (126.67° C)                              14,000 (4270 m)                                                                           206 (96.67° C)                                                                       290 (143.33° C)                              15,000 (4575 m)                                                                           226 (107.78° C)                                                                      305 (151.66° C)                              16,000 (4880 m)                                                                           248 (120.00° C)                                                                      320 (160.00° C)                              18,000 (5490 m)                                                                           300 (148.89° C)                                                                      350 (176.67° C)                              20,000 (6100 m)                                                                           340 (171.11° C)                                                                      380 (193.33° C)                              22,000 (6710 m)                                                                           380 (193.33° C)                                                                      410 (210.00° C)                              ______________________________________                                         *Metric Equivalents                                                      

Fluid loss is the number of milliliters or cubic centimeters of liquidforced through No. 50 Whatman filter paper or through 325 mesh screenaccording to API publication RP-10B (Section 8).

                  TABLE I                                                         ______________________________________                                         Predictable Behavior                                                         ______________________________________                                        Lone Star Class H Cement                                                      38% H.sub.2 O                                                                          Thickening Times                                                              Hours:Minutes                                                        SML*     API Casing Simulation Tests                                          % Retarder                                                                             8,000'    10,000'   12,000' 14,000'                                  ______________________________________                                        0.20     2:35      2:04      1:33    --                                       0.25     4:20      2:37      --      --                                       0.30     5:50      3:11      2:31    1:58                                     0.35     --        5:20      --      --                                       0.40     --        --        4:12    3:01                                     0.50     --        --        7:18    3:47                                     0.60     --        --        --      4:09                                     0.70     --        --        --      5:12                                     ______________________________________                                        Lone Star Class H Cement                                                      46% H.sub.2 O                                                                 0.16     2:43      --        --      --                                       0.20     --        2:25      2:15    1:55                                     0.24     3:51      --        --      --                                       0.30     6:40      3:28      3:01    2:32                                     0.34     --        --        3:58    --                                       0.35     --        6:13      --      --                                       0.38     --        --        4:17    --                                       0.40     --        11.22     --      3:32                                     0.44     --        --        5:37    --                                       0.60     --        --        --      6:10                                     ______________________________________                                         *Sulfomethylated lignin retarder.                                        

Increasing the retarder concentration results in corresponding increasein thickening time until a saturation point is reached. Beyond thispoint, slight increases in the retarder concentration result in greatlyincreased thickening times.

                  TABLE II                                                        ______________________________________                                        Set Times Obtained with Commercially Available                                Calcium Lignosulfonate and the Sodium Salt of                                 Sulfomethylated Lignin.sup.a                                                                         Percent  Set Times -                                                 Percent  Sodium   Hours:Minutes                                               Retarder Chloride API Casing                                                  (by wt.  (by wt.  Simulation Tests                              Retarder      Cement   water)   14,000' - 206° F                       ______________________________________                                        Sulfomethylated Lignin                                                                      0.3       0       1:58                                                        0.4      0        3:01                                                        0.5      0        3:47                                                        0.6      0        4:09                                                        0.7      0        5:12                                          Calcium Lignosulfonate                                                                      0.3      0        3:25                                                        0.4      0        4:05                                                        0.5      0        1:34.sup.b                                                  0.6      0        1:35.sup.b                                    Sulfomethylated Lignin                                                                      0.3      18.0     1:44                                                        0.4      18.0     2:27                                                        0.5      18.0     2:45                                                        0.6      18.0     3:42                                                        0.7      18.0     4:33                                                        0.8      18.0     5:12                                          Calcium Lignosulfonate                                                                      0.2      18.0     1:32.sup.b                                                  0.3      18.0     1:40.sup.b                                                  0.4      18.0     1:48.sup.b                                                  0.5      18.0     2:05.sup.b                                                  0.6      18.0     2:40.sup.b                                    ______________________________________                                         .sup.a All slurries consisted of 800 grams Lone Star Class H Cement with      304 grams (38%) water, and indicated amounts of additive and sodium           chloride.                                                                     .sup.b Slurry gelation was observed, i.e., viscosity reached 70 units of      consistency but slurry had not developed significant compressive strength     at that time. Others reached a viscosity of 70 units and set with             compressive strength at approximately the same time.                     

AT higher temperatures slurries containing the conventional retardertend to form unpumpable heavy gels prior to development of significantcompressive strength, however, use of the sulfomethylated compoundyielded slurries which were well dispersed until final hard set of thecement was obtained. This is illustrated in Table II which lists the settime and percent added retarder for both fresh and salt water slurriescontaining either the commercially available calcium salt oflignosulfonate or the sodium salt of the new sulfomethylated compound.As noted in the table, many of the slurries containing the calcium salttended to form heavy gels (i.e., slurry is unpumpable and thus,considered set when the viscosity reaches 70 units of consistency eventhough it may have gelled with no compressive strength at that time);this results in an erratic dependence of set time on retarderconcentration. For example, in the fresh water slurries, increases inretarder concentration in excess of approximately 0.4% (Table II) resultin decreased rather than the expected increased set times; this effectis not found for the new compound which shows a reasonable set timeincrease as the retarder concentration is increased in both fresh andsalt water slurries.

Predictable Behavior One Cement to Another

                  TABLE III                                                       ______________________________________                                        Predictable Behavior One Cement to Another                                    Effect of Cement Brand on Set Time.sup.a                                                              Percent                                                                       Additive Set Time -                                                           (by wt.  Hours:Minutes                                                        of       API Casing -Type of Cement Additive cemen                                     t) 14,000'- 206° F                    ______________________________________                                        Lone Star Class H                                                                         Sulfomethylated                                                    (Maryneal).sup.b                                                                         Lignin      0.5      3:37                                         Lone Star Class H                                                                         Calcium                                                            (Maryneal).sup.b                                                                         Lignosulfate                                                                              0.5      1:34.sup.h                                   Lone Star Class H                                                                         Sulfomethylated                                                    (New Orleans).sup.c                                                                      Lignin      0.5      2:45                                         Lone Star Class H                                                                         Calcium                                                            (New Orleans).sup.c                                                                      Lignosulfate                                                                              0.5      0:40.sup.h                                   Trinity Class H.sup.d                                                                     Sulfomethylated                                                               Lignin      0.5      2:46                                         Trinity Class H.sup.d                                                                     Calcium                                                                       Lignosulfate                                                                              0.5      3:02.sup.h                                   Southwestern                                                                              Sulfomethylated                                                    Class H.sup.e                                                                            Lignin      0.5      3:19                                         Southwestern                                                                              Calcium                                                            Class H.sup.e                                                                            Lignosulfate                                                                              0.5      4:05                                         Oklahoma Class H.sup.f                                                                    Sulfomethylated                                                               Lignin      0.5      3:00                                         Oklahoma Class H.sup.f                                                                    Calcium                                                                       Lignosulfate                                                                              0.5      3:45.sup.h                                   Dyckerhoff Class B.sup.g                                                                  Sulfomethylated                                                               Lignin      0.5      2:44                                         Dyckerhoff Class B.sup.g                                                                  Calcium                                                                       Lignosulfate                                                                              0.5      2:45                                         ______________________________________                                         .sup.a Slurries consisted of 800 grams indicated cement, 304 grams (38%)      water (by wt. of cement), and additive with the exception of the slurries     containing Dyckerhoff Class B which contained 368 grams (46%) water.          .sup.b Cement manufactured by Lone Star Industries, Inc., Maryneal, Texas     .sup.c Cement manufactured by Lone Star Industries, Inc., New Orleans,        Louisiana.                                                                    .sup.d Cement manufactured by Trinity, Portland Cement Division, Dallas,      Ft. Worth, Houston, Texas.                                                    .sup.e Cement manufactured by Southwestern Portland Cement Company, El        Paso, Texas.                                                                  .sup.f Cement manufactured by OKC Corporation, Pryor, Oklahoma.               .sup.g Cement manufactured by Dyckerhoff Zementwerke AG,                      Wiesbaden-Biebrich, Germany.                                                  .sup.h These slurries gelled prior to hard set.                          

At constant concentration of the new retarder, reasonably consistent settimes are obtained for slurries containing cements produced by differentmanufacturers (Table III). This contrasts with the similar results forcalcium lignosulfonate which vary drastically from one cement toanother.

                  TABLE IV                                                        ______________________________________                                         Slurry Gelation Effect                                                       Viscosity versus Pumping Time for the Slurries                                Containing Calcium Lignosulfonate or the Sodium                               Salt of Sulfomethylated Lignin                                                                          Pumping Times                                                                 Hours:Minutes                                                                           Viscosity                                 Type             Percent  14,000' API                                                                             In Units of                               of Cement                                                                             Additive.sup.d                                                                         Additive Casing - 206° F                                                                  Consistency.sup.e                         ______________________________________                                        Lone Star                                                                             SML      0.5      0:00      9                                         Class H                   0:30      6                                         (Maryneal)                0:45      6                                                                   1:00      6                                                                   1:15      6                                                                   1:30      6                                                                   2:00      12                                                                  2:15      21                                                                  3:00      26                                                                  3:15      29                                                                  3:30      31                                                                  3:47.sup.b                                                                              70                                                NaLS     0.5      0:00      1                                                                   0:30      4                                                                   0:45      13                                                                  1:00      37                                                                  1:15      41                                                                  1:30      45                                                                  1:34.sup.c                                                                              70                                        ______________________________________                                         .sup.a Slurries consisted of cement, 38% water and additive.                  .sup.b Slurry reached a viscosity of 70 units and set with compressive        strength at approximately the same time.                                       .sup.c Slurry reached a viscosity of 70 units but had no compressive         strength until approximately two hours later.                                 .sup.d SML is sulfomethylated lignin and NaLS is sodium lignosulfonate.       .sup.e Consistency measured directly in units of consistency according to     API pulbication RP-10B.                                                  

                  TABLE V                                                         ______________________________________                                         Lower Temperatures                                                           Set Times Obtained with Calcium Lignosulfonate                                and the Sodium Salt of Sulfomethylated LIgnin                                            Percent                                                                       Retarder  Set Times -                                                                              Hours:Minutes                                            (by wt.   API Casing Simulation Tests                               Retarder  Cement)   10,000'    12,000'                                       ______________________________________                                        Sulfomethylated                                                               Lignin.sup.a                                                                             0.3       --         2:30                                                     0.4       --         3:57                                                     0.5       --         8:00                                          Calcium                                                                       Lignosulfonate.sup.a                                                                     0.3       --         3:10                                                     0.4       --         2:21                                                     0.6       --         1:40                                          Sulfomethylated                                                               Lignin.sup.b                                                                             0.08      2:58       --                                                       0.12      3:29       --                                                       0.16      4:00       --                                                       0.20      4:50       --                                                       0.24      6:33       --                                            Calcium                                                                       Lignosulfonate.sup.b                                                                     0.40      1:44.sup.c --                                                       0.80      3:20.sup.c --                                            ______________________________________                                         .sup.a Slurries consisted of Dyckerhoff Class G, 44% water and indicated      additive.                                                                     .sup.b Slurry consisted of Longhorn Class H Cement with 44% water, 35%        coarse silica flour (60-140 mesh), 0.75% CFR-2 friction reducer and 18%       sodium chloride salt. CFR-2 is beta-naphthalene sulfonic acid condensed       with formaldehyde and mixed with 10% polyvinyl pyrrolidone. CFR-2 is          described in U.S. Pat. No. 3,359,225 which is incorporated herein by          reference.                                                                    .sup.c Slurries showed severe gelation effects.                          

                  TABLE VI                                                        ______________________________________                                        Compressive Strength                                                          Class H Cement with 38% Water                                                 Retarder Concentration Giving 4.0 Hr. Pumping                                 Time on 12,000 ft. Schedule                                                   Slurries Pumped 2 hrs. on 12,000 ft. Schedule                                 and placed in Autoclaves at Indicated                                         Temperature                                                                   Compressive Strength     Compressive Strength                                 Using Conventional       Using SML                                            Lignosulfonate Retarder  Cement Retarder                                      (PSI)         Temperature                                                                              (PSI)                                                8 hrs.                                                                              12 hrs. 24 hrs. ° F                                                                             8 hrs.                                                                              12 hrs                                                                              24 hrs                             ______________________________________                                        NS*   290     2260    170       650  1690  2790                               NS    2080    2660    200      1010  2020  3980                               NS    2270    2840    230      1670  2800  4260                               1360  3480    3310    260      2040  3660  5420                               ______________________________________                                         *Not Set                                                                 

Compressive strength tests were run on slurries containing calciumlignosulfonate or sulfomethylated lignin. The cement employed in thesetests was Lone Star Class H. In these tests, slurries containingretarder to give four hour pumping times on a 12,000' casing schedulewere used. The slurries were pumped two hours at a 12,000' casingschedule and placed in autoclaves at four different temperatures tosimulate the actual conditions encountered from the top to the bottom ofa cement column in a well. The compressive strengths were thendetermined after 8, 12 and 24 hours according to API publication RP-10B(Section 6). After 8 hours, the slurries containing lignosulfonate hadnot set at the lower tempertures. However, the slurries containingsulfomethylated lignin were all set with significant strengths. Thesulfomethylated lignin slurries consistently showed more rapid strengthdevelopment throughout these tests.

                                      TABLE VII                                   __________________________________________________________________________    Compatibility With Fluid Loss Additives                                       Compatibility of New Sulfomethylated Lignin and Common Fluid Loss             Additives.sup.a                                                               Consistometer      Percent                                                                            Fluid Loss Additive                                                                       Sodium                                     Readings          Retarder                                                                           1.sup.b                                                                             2.sup.c                                                                             Chloride                                                                           Fluid                                at 100° F (Poise)                                                                         By Wt.                                                                             % By Wt.                                                                            % By Wt.                                                                            % By Wt.                                                                           Loss                                 Initial                                                                            Final Retarder                                                                              Cement                                                                             Cement                                                                              Cement                                                                              Water                                                                              (cc)                                 __________________________________________________________________________               Sulfomethylated                                                    9    8     Lignin  0.5  0.6   --0-- -- --                                                                               44                                             Calcium                                                            9    10    Lignosulfonate                                                                        0.5  0.6   --0-- --0--                                                                              141                                             Sulfomethylated                                                    10   10    Lignin  0.5  0.6   --0-- 18.0  98                                             Calcium                                                            10   10    Lignosulfonate                                                                        0.5  0.6   --0-- 18.0 188                                             Sulfomethylated                                                    12   12    Lignin  0.5  --0-- 0.6   --0--                                                                               38                                             Calcium                                                            10   10    Lignosulfonate                                                                        0.5  --0-- 0.6   --0--                                                                              137                                             Sulfomethylated                                                    12   12    Lignin  0.5  --0-- 0.6   18.0  82                                             Calcium                                                            11   11    Lignosulfonate                                                                        0.5  --0-- 0.6   18.0 154                                  __________________________________________________________________________     .sup.a All slurries contained Lone Star Class H Cement, 28% water, and        indicated amounts of retarder, Halliburton fluid loss additive, and sodiu     chloride. After mixing, the slurries were stirred on the Halliburton          Consistometer for 20 minutes at 100° F and fluid loss determinatio     conducted at 100 PSI pressure on a 325 mesh screen at the same                temperature.                                                                  .sup.b 56% HEC (hydroxyethyl cellulose)with 44% CFR-2.                        .sup.C 60% HEC, 20% defoamer with 20% CFR-2.                             

                                      TABLE VIII                                  __________________________________________________________________________    Dispersant and Fluid Loss Properties in Gel Cement Slurries                   Class H Cement                                                                12% Gel                                                                       11.46 gal. water/sack                                                                                            Fluid Loss                                                                    cc/30 Min.                                                                    100 PSI                                             % Addition                                                                          Fann Data           No. 50                                                                             1000 PSI                                       (By wt.                                                                             Shear Stress lb/ft.sup.2 at 80° F                                                          Whatman                                                                            325 Mesh                              Retarder Cement)                                                                             600 RPM                                                                            300 RPM                                                                            200 RPM                                                                            100 RPM                                                                            Paper                                                                              Screen                                __________________________________________________________________________    Sulfomethylated                                                               Lignin    --0--                                                                              1.22 1.16 1.12 1.05 190  372                                            0.34  0.47 0.34 0.31 0.26 132  265                                            0.52  0.42 0.27 0.21 0.17 104  188                                   Calcium Sodium.sup.a                                                          Lignosulfonate                                                                         0.34  0.58 0.47 0.43 0.37 149  258                                            0.52  0.69 0.56 0.51 0.46 113  217                                   __________________________________________________________________________     .sup.a A mixed calcium-sodium lignosulfonate is used in gel cement            slurries instead of simple calcium lignosulfonate due to the tendency of      the latter to gel slurries of this type.                                 

Sulfomethylated lignin functions in gel cement slurries as a dispersantand fluid loss additive. Previously, two separate retarders wererequired; one for non-gel slurries which was calcium lignosulfonate andanother for gel slurries which was calcium sodium lignosulfonate.

                  TABLE IX                                                        ______________________________________                                        Extension with Tartaric Acid                                                  Set Times Obtained with a Mixture of the Sodium                               Salt of Sulfomethylated Lignin and Tartaric Acid                              in a 2:1 Weight Ratio*                                                                 Set Times                                                            % Retarder                                                                             Hours:Minutes                                                        (By Wt.  API Casing Simulation Tests                                          Cement)  16,000'   18,000'   20,000' 22,000'                                  ______________________________________                                        0.4      1:55      --        --      --                                       0.5      4:20      --        --      --                                       0.6      5:57      1:40      --      --                                       0.8      --        2:31      --      --                                       0.9      --        3:43      --      --                                       1.0      --        4:34      --      --                                       1.1      --        5:13      --      2:00                                     1.2      --        --        3:43    --                                       1.3      --        --        --      2:28                                     1.6      --        --        5:10    --                                       1.8      --        --        6:32    3:12                                     2.0      --        --        --      3:25                                     2.6      --        --        --      4:10                                     ______________________________________                                         *All slurries consisted of Lone Star Class H Cement, 35% SSA-1, 54% water     and indicated amounts of retarder. SSA-1 is fine silica flour which is        added to cement slurries at high temperature to prevent strength              retrogression. Over 97% of the silica particles pass through a 200-mesh       (U.S. Std. Sieve Series) screen.                                         

                  TABLE X                                                         ______________________________________                                        Extension of Set Times of Slurries Containing                                 Sulfomethylated Lignin by the Addition of Borax                               Percent    Percent                                                            Sulfomethylated                                                                          Borax      Set Time - Hours:Minutes                                Lignin (By Wt.                                                                           (By Wt.    API Casing Schedule                                     Cement)    Cement)    15,000'    16,000'                                      ______________________________________                                        0.7        0.6        3:00       --                                           0.8        0.6        4:22       --                                           0.9        0.6        5:12       --                                           0.4        0.7        --         1:54                                         0.6        0.7        --         3:54                                         0.8        0.7        --         5:20                                         0.95       0.7        --         7:10                                         ______________________________________                                    

Set times obtained with sulfomethylated lignin can be extended by theaddition of boric acid or water soluble salt of boric acid (e.g., saltsof ammonia, alkali or alkaline earth metals). This extension makespossible the use of the sulfomethylated lignin retarder at highertemperatures. Examples of extenders of this type are:

1. Boric acid,

2. Na₂ B₄ O₇ . 10 H₂ O (Borax),

3. Na₂ B₅ O₈ . 5 H₂ O,

4. kb₅ o₈ . 4 h₂ o,

5. li₁ B₅ O₈ . 5 H₂ O,

6. naBO₂ . 4 H₂ O,

similar compounds and mixtures thereof.

We claim:
 1. A process for sealing at an elevated temperature a zonepenetrated by a wellbore using a high efficiency non-gelling hydrauliccement retarder composition having a high degree of predictability forcontrolling rheology and setting time comprising mixing an aqueousslurry of hydraulic cement with up to about 2% on a dry cement weightbasis of a retarder consisting essentially of a low molecular weightsulfoalkylated lignin; wherein the concentration of retarder iscalculated to control the setting time of said hydraulic cement toexceed the pumping time; wherein the sulfoalkylated lignin has amolecular weight in the range of about 2,000-10,000 and which issubstantially sulfoalkylated on the benzene ring of the lignin moleculein the position ortho to the free phenolic hydroxy group and thesulfonate group is attached to the ortho position by an alkylideneradical having one to three carbon atoms; pumping said hydraulic cementmixture into said zone and maintaining said hydraulic cement mixture insaid zone until a high compressive strength is attained.
 2. A processfor sealing at an elevated temperature a zone penetrated by a wellboreusing a high efficiency non-gelling hydraulic cement composition havinga high degree of predictability for controlling rheology and settingtime comprising mixing an aqueous slurry of hydraulic cement with up toabout 2% on a dry cement weight basis of a retarder consistingessentially of at least one water soluble hydroxy carboxylic acid and alow molecular weight sulfoalkylated lignin; wherein the concentration ofretarder is calculated to control the setting time of said hydrauliccement to exceed the pumping time; wherein the weight ratio of acid tolignin is in the range of about 1:0.1-5.0; wherein said carboxylic acidis a substantially linear aliphatic acid having at least one terminalcarboxyl group in the form of acid, salt of mixtures thereof; whereinsaid sulfoalkylated lignin has a molcular weight in the range of about2,000-10,000 and which is substantially sulfoalkylated on the benzenering in the lignin molecule in the position ortho to the free phenolichydroxy group and the sulfonate group is attached to the ortho positionby an alkylidene radical having one to three carbon atoms; pumping saidhydraulic cement mixture into said zone without gelation and maintainingsaid hydraulic cement mixture in said zone until a high compressivestrength is attained.
 3. In a process for cementing a zone at anelevated temperature by pumping an aqueous hydraulic cement slurry intosaid zone, the improvement of controlling the setting time of saidcement and preventing gelation of said cement by mixing with saidhydraulic cement a high efficiency non-gelling retarder consistingessentially of a mixture of at least one water soluble hydroxycarboxylic acid and a low molecular weight sulfoalkylated lignin;wherein the concentration of retarder is calculated to control thesetting time of said hydraulic cement to exceed the pumping time;wherein the weight ratio of said acid to lignin is in the range of about1:0.1-5.0; wherein the carboxylic acid is a substantially linearaliphatic acid having at least one terminal carboxyl group in the formof acid, salt or mixtures thereof; wherein said sulfoalkylated ligninhas a molecular weight in the range of about 2,000-10,000 and which issubstantially sulfoalkylated on the benzene ring in the lignin moleculein the position ortho to the free phenolic hydroxy group and thesulfonate group is attached to the ortho position by an alkylideneradical having one to three carbon atoms.